Perennials – Echter's Garden Talk

Frost Hardiness

Plants vary in their ability to tolerate cold temperatures and harsh conditions. Different areas in Colorado can have drastically different climates and varying weather conditions each year. All of these factors make it difficult to determine a “safe date” to plant.

We have complied a list of plants ranging from “Very Hardy” to “Tender”. We offer recommendations on planting dates in the Denver area for each group but caution that these dates are approximations. We strongly recommend hardening off your plants (especially annuals) before planting and keeping a close eye on the weather. If needed, covering plants during cold snaps or chilly nights can help protect them.

Very Hardy Plants

Very hardy plants can typically be planted 7 weeks before the average last frost date. In the Denver Metro Area, this is usually after April 1st.

Very Hardy Flowers

Alyssum
Anchusa
Centaurea
Dracaena
Dusty Miller
Larkspur
Pansy
Snapdragon
Sweet Pea
Viola

Very Hardy Vegetables

Asparagus
Fennel
Onions
Peas
Potato
Radish
Strawberries

Hardy Plants

Hardy plants can typically be planted 5 weeks before the average last frost date. In the Denver Metro Area, this is usually after April 20th.

Hardy Flowers

Arctotis
Artemesia
Baby Blue Eyes
Bellis
Calendula
Carnation
Cerastium
Columbine
Dianthus
Diascia
Erysimum
Flowering Kale
Heuchera
Iberis
Lavender
Lenten Rose
Lobelia
Lupine
Matricaria
Myosotis
Nemesia
Osteospermum
Phlox
Roses
Vinca Vine

Hardy Vegetables

Broccoli
Brussels Sprouts
Cabbage
Cauliflower
Kohlrabi
Lettuce
Pak Choi
Perennial Herbs
Radicchio
Rhubarb
Spinach

Half Hardy Plants

Half hardy plants can typically be planted 3 weeks before the average last frost date. In the Denver Metro Area, this is usually after May 1st.

Half Hardy Flowers

Anagallis
Angelonia
Bacopa
Bells of Ireland
Calibrachoa
California Poppy
Campanula
Coreopsis
Cosmos
Datura
Delphinium
Dichondra
Euphorbia
Felicia Daisy
Gazania
Gerbera
Gomphrena
Lotus Vine
Mexican Feather Grass
Ornamental Grasses
Pennisetum
Penstemon
Petunia
Phlox
Pincushion Flower
Regal Geranium
Ruby Grass
Rudbeckia
Sanvitalia
Stocks
Strawflower
Sutera
Sweet Pea
Trifolium
Verbena

Half Hardy Vegetables

Artichoke
Celery
Leek

Tender Plants

Tender plants can be planted when there is no longer danger of frost. In the Denver Metro Area, this is usually after May 20th.

Tender Flowers

Abutilon
Achimenes
Ageratum
Alternanthera
Alternaria
Amaranthus
Angelonia
Argyranthemum
Asparagus Fern
Aster
Banana
Balsam
Begonia
Bidens
Bouganvilla
Bower Vine
Brachycome
Browallia
Brunfelsia
Caladium
Calibrachoa
Calla Lily
Callopsis
Campanula
Canna
Cardinal Climber
Celosia
Chrysanthemum
Chrysocephalum
Cigar Plant
Clematis
Cleome
Coleus
Cordyline
Coreopsis
Crassula
Crossandra
Cuphea
Dahlberg Daisy
Dahlia
Dallas Fern
Daylily
Dipladenia
Elephant Ears
Evolvulus
Ferns
Fiber Optic Grass
Four O’Clock
Fuchsia
Geranium
Gloriosa Lily
Guara
Heliotrope
Hibiscus
Impatiens
Iresene
Iris
Jasmine
Lantana
Lisianthus
Livingstone Daisy
Lothospermum
Lysmachia
Mandevilla
Marguerite Daisy
Marigolds
Mecardonia
Melampodium
Millet
Mimulus
Moon Vine
Monopsis
Morning Glory
Napa Valley Fern
Nasturtium
Nemesia
Nicotiana
Nierembergia
Nolana
Oleander
Oxalis
Pampas Grass
Pentas
Periwinkle
Perilla
Plectranthus
Polka Dot Plant
Polygonum
Portulaca
Rudbeckia
Salpiglopssis
Salvia
Scarlet Runner Bean
Scaevola
Schizanthus
Sedum
Statice
Streptocarpella
Sunflower
Swan River Daisy
Sweet Potato Vine
Tithonia
Thumbergia
Torenia
Trachelium
Trailing Portulaca
Tropical Hibiscus
Tropical Water Plants
Veronica
Vinca
Zinnia

Tender Vegetables

Annual Herbs
Cantaloupe
Corn
Cucumber
Eggplant
Okra
Peanuts
Peppers
Pumpkin
Squash
Tomato
Watermelon

Deer Resistant Plant List

Use this handy list to help you choose plants that deer usually don’t find
appetizing in the landscape

Keep in mind: No plant is absolutely guaranteed to be deer proof! If deer are hungry enough, they’ll eat anything — even plants they don’t like — especially in the winter when food sources are scarce. The plants below are not usually a deer’s top choice.

Bulbs
Allium
Daffodils
Garlic
Iris
Onions

Herbs
Marjoram
Mints
Oregano
Thyme

Perennials
Astilbe
Apache Plume
Basket of Gold
Bleeding Heart
Chocolate Flower
Clematis
Coneflower
Creeping Phlox
Daylilies
Dianthus
Delphinium
Euphorbia
Flax
Foxglove
Globe Thistle
Golden Banner
Goldenrod
Honeysuckle
Lamb’s Ear
Lavender
Lenten Rose
Liatris
Lily of the Valley
Mexican Hat Coneflower
Penstemon
Peony
Poker Plant
Poppies
Prairie Zinnia
Prickly Pear
Purple Prairie Clover
Russian Sage
Salvia
Sedum
Shasta Daisy
Soapworts
Snowdrops
Snow-in-Summer
Virginia Creeper
Western White Clematis
Yarrows
Yucca

Shrubs
Alpine Currant
Austrian Copper Rose
Big Western Sage
Boulder Raspberry
Chokecherry
Common Hackberry
Common Juniper
Creeping Mahonia
Curl-leaf Mountain Mahogany
Euonymus
Fernbush
Fragrant Sumac
Golden Currant
Hancock Coralberry
Leadplant
Lilacs
Mountain Ninebark
Nanking Cherry
Oregon Grape Holly
Persian Yellow Rose
Potentilla
Pyracantha
Quince
Rabbitbrush
Red Twig Dogwood
Rose of Sharon
Santolina
Silver Buffaloberry
Snowberry
Spirea

Trees
Colorado Spruce
Concolor Fir
Douglas Fir
Gambel’s Oak
Honeylocust
Lodgepole Pine
Pinyon Pine
Rocky Mountain Maple

Make sure you’re not planting a buffet of deer favorites in your landscape! Deer show a particular preference for narrow-leafed evergreens, especially arborvitae and fir. They also love tender, green plants like hostas, daylilies, and English ivy. You might also want to employ some other strategies in addition to deer-resistant plant choices.

Why Start Seeds Indoors?

“All the flowers of all the tomorrows are in the seeds
of today.”

~ Indian Proverb

Why should you consider starting this year’s garden indoors? Why not just wait until the last frost date passes, and plant seeds directly in the garden beds? There are lots of reasons — especially in Colorado — why getting a head start on the season is such a good idea.

Get a Jump on the Growing Season
Besides just being a lot of fun, one of the best reasons to start seeds indoors is that here in Colorado, the growing season tends to be rather short — even more so in the mountain communities! Being able to set young plants out (as opposed to sowing seed directly) allows your crops to be a few weeks ahead at the beginning of the season, and that means earlier harvests of those tasty spring and summer veggies!

Grow a Warm-Season Crop in a Short-Season Climate
Everyone’s favorite summer vegetables usually have a long growing season. Beans, corn, and tomatoes can require anywhere from 60-100 days from seed to maturity, and those bright October pumpkins require 120 days! If you have to wait for the outdoor soil to reach the optimal temperature for growing, you’ll miss out on valuable growing days. Considering Colorado’s growing season is only an average of 150 days, getting started earlier sure can be an advantage. Start these popular summer crops weeks earlier by seeding indoors, and start enjoying those juicy tomatoes a little sooner!

When it comes to starting perennial flowers from seed, you may be able to get first-year blooms on flowers that usually don’t flower until their second year in the garden. Varieties that benefit from a head start indoors are: Asters, Black-eyed Susans, Coleus, and Lavender.

Grow a Variety That Isn’t Offered as a Starter Plant
You might also consider starting from seed if you’d like to try varieties of veggies that your local garden center doesn’t offer as “starts” or young plants in the spring. By growing your own vegetables from seed, you have more varieties available to you. For example, while we grow more than 200 different types of vegetable plants each year here at Echter’s, we can’t offer every variety of every crop. Sometimes there may be something you’d like to grow in your garden that we don’t offer. Seed gardening is a great way to grow those extra-special varieties that may not be commonly available.

Fun for kids
If you’ve got little gardeners around the house, the process of planting a dry, dead looking seed into soil, then watching it sprout and grow into a live plant is nothing less than magic! It can also provide a valuable lesson in where our food comes from. One small seed can grow a lot more than a plant. It just might grow a lifelong love of gardening.

A Word of Caution
With some crops, it can be beneficial to just wait until after the last spring frost and sow directly into the garden. This tends to be true of root vegetables like radishes and carrots. Root crops are fussy about being transplanted because no matter how careful you are during the transplanting process, there’s bound to be some minor root damage, and that will show up in the final vegetable. Direct sowing produces better results in those plants.

There’s so much satisfaction that comes from starting your garden from seed. You control what’s going into your food crops, you can save money, and you have access to a greater variety of plants. One of the nicest things about seed gardening is having something green and growing during the grey days of winter. Pay us a visit, and be inspired by all the crops and varieties that are available this year!

The Beautiful Leaf

This time of year we are all so enamored by flowers that it’s easy to overlook the value of colorful foliage in the garden. Colored leaves come in many hues, from shades of purple-reds to bright chartreuse greens to shades of orange. I’m not talking about fall color, here. These colorful leaves can be enjoyed all summer in their bright hues. Colorful foliage makes container gardens stand out from the crowd. In perennial beds, colorful leaves can provide beauty when plants are between bloom cycles. Colorful trees and shrubs stand out against the customary hues of green, becoming focal points of the garden.

Under the Sea Coleus "Bonefish" is a striking plant with bright chartreuse, serrated edges that add both texture and color. — Under the Sea Coleus “Bonefish” is a striking plant with bright chartreuse, serrated edges that add both texture and color.

Under the Sea Coleus, from Hort Couture Plants, is a favorite for container gardens. They come in several color combinations and sizes from tall to small. Each is unique in the world of coleus. All perform well in sun to part sun, in our Colorado climate. Small leaved varieties sail through the heat of summer. Large leaved cultivars, like “King Crab” will benefit from some shade in the afternoon.

Most people don’t think about trees being colorful unless it’s fall. There are, however, quite a few that shouldn’t be overlooked.

Japanese Maple “Shiraz”. Best grown in a semi shaded area, protected from arid winter winds.

Royal Red Norway Maples have large,richly colored, dark burgundy/mahogany leaves. These trees can reach 35′-40′ tall, providing ample shade. They tolerate pollution well, making them a great choice where there is high traffic.

Tricolor Beech have a decidedly pyramid shape while young. Like many of us, they round out a bit with age. They reach 25'-35' tall. They will do best in an eastern or north eastern exposure, in a partial sun area. — Tricolor Beech have a decidedly pyramid shape while young. Like many of us, they round out a bit with age. They reach 25′-35′ tall. They will do best in an eastern or north eastern exposure, in a partial sun area.

If landscapes had a sense of fashion, then dark leaved plants would be the “little black dress”. They are always in style and every garden should have at least one in the wardrobe. Japanese maples provide interesting structural form and many have colorful leaves that will turn a shady area into a mystical garden.

Heuchera Blackberry Ice is a staff favorite. The dark berry colored leaves dress up shady borders. Try using them in shady container gardens too.

Heuchera is the coleus of perennials. Every year, more new cultivars are introduced. Most are relatively compact, making it easy to add them to existing garden beds or container gardens.

Heuchera Amber Lady shows off it's luscious leaves. Grow them in shady gardens. — Heuchera Amber Lady shows off it’s luscious leaves. Grow them in shady gardens.

Barberry are among the most versatile, sun-loving shrubs for Colorado. They come in multiple sizes and shapes. Most have colorful leaves, ranging from bright red/orange to lemony greens. Tiny or tall, there’s so many shapes and sizes, it’s difficult to choose. Their thorns make them less suitable for areas where people may brush against them. That said, those thorn make them a great choice as a deterrent when planted around a home’s foundation, under windows. Their berries provide food for birds and their density provides shelter.

Barberry Orange Rocket is a columnar shrub, ideal for creating a hedge in a narrow space. They can also be used as a centerpiece in container gardens. Just be sure to plant it in the ground in fall.

Barberry comes in many colors and sizes. They dress up sunny garden areas and can be used in borders, as hedges or as accent shrubs. Few shrubs are as versatile.

Evergreens, in both tree and shrub forms, are hardy additions to Colorado gardens. They thrive in full sun and manage to look fabulous despite our arid late summer conditions. They take wild temperature swings in stride, making them ideal in a climate with more than 40 freeze/thaw cycles each year.

Juniper "Sea of Gold" is a dramatic shrub that provides garden color year round. — Juniper “Sea of Gold” is a dramatic shrub that provides garden color year round.

Say the word “juniper” and some people cringe, thinking of prickly shrubs filled with spider webs. Today’s junipers come in many textures and sizes. Some are great for use as low growing shrubs. Others, like the one pictured, are drama queens, with soft needles and dense branching.

There’s more than one way to enjoy a colorful garden. So try some colorful leaves in your garden and see how dramatically they change the look of your landscape.

Itoh Peonies

Peonies are one of the most adored spring flowers. There are some recent hybrids that are truly spectacular. Itoh peonies are named for hybridizer Toichi Itoh. They are hybrids between tree peonies and herbaceous peonies, a.k.a intersectional hybrids.

The best traits of both parent plants come together to give these plants incredible garden performance. Strong stems are capable of supporting their sizable blooms. No more nodding flowers that can’t be enjoyed in their full glory. The strong stems also mean they make fabulous cut flowers. Itoh peonies have increased vigor, durability, and long life in the garden. In addition to all those improvements, Itoh peonies produce primary and secondary buds, which means many more flowers, up to 50 on mature plants.

Like their herbaceous parent, they die back to the ground in winter and often have a light fragrance. Like all peonies, they should be mulched well in the fall to stabilize the ground temperature during the winter freeze/thaw cycles.

While we’re on the topic of peonies, let’s dispel a common myth. Peonies do not need ants in order to bloom. Ants are often seen on peony blooms simply because they are attracted to their sweet nectar secreted by peonies as they bud. The ants don’t harm the flowers. They are just after the carbohydrates in the nectar. If you are concerned about ants on your peonies when you are ready to display them indoors as cut flowers, dip the blooms in water to help rinse away potential hitchhikers.

Fall Containers Not Just for Pansies Anymore!

Fall automatically brings to mind changing colors and inspires us to change out our tender summer annuals for new shades. Traditional pansies and mums are a classic seasonal adornment to bridge the gap from summer to winter, but have you tried combining them with other late-season color?

Try some of these ideas and you’ll have containers you’ll love through to Thanksgiving! Most of these are perennials, so they can be pulled out and planted in the ground when you are ready to change out for holiday decorations.

Ornamental Kale/Cabbage- most commonly found as large rosettes in shades of green, icy blue-green, purple, pink, or red, kales are long-lasting and easy to maintain. Annual.

Sedum- covers a wide range of colors, textures, and heights. Some varieties are only a few inches tall, while others such as Autumn Joy can reach 2 feet. Mixing varieties in the same container can produce an amazing results—a tall, billowing sedum in the back of a pot can be nicely balanced by ‘Dragons Blood’ spilling off the front in shades of red (or ‘Angelina’ for yellow). Many varieties have quarter-size fleshy leaves that shift in tone from cool blues to fall tones.

Euphorbias- flower vividly in the spring and have red/orange/yellow leaves as fall sets in. Foliage texture can be rigidly upright to wispy and delicate. Some have a full & fluffy look, while others are more airy.

Heucheras/ Coral Bells – Available in a wide range of fall colors from deep, rich purples to caramel. Green varieties blend to reds and purples as the season progresses and add a sophisticated flair.

Rudbeckia- Plants (and flowers!) can be mammoth or miniscule depending on variety. ‘Toto’ reaches a pint-sized 1’ in height and bronzed ‘Autumn Colors’ will reach 2+’. Also in the tall group are ‘Indian Summer’ and ‘Prairie Sun’. ‘Goldsturm’ has smaller flowers but a ton of them.

Ornamental Grasses- Easy fillers that come in a range of tones. Provide structure and overall form for the combination.

Now that you have some ideas, how to put them together? Generally speaking, container plantings look best when you follow the adage “Thriller, Spiller, Filler”. Sedums can be any of those, depending on the varieties you select. Euphorbias are likely to be fillers or thrillers. Rudbeckias make a great thriller, and heucheras are lovely fillers. Adding back in the mums and pansies, a large patio pot might contain:

1 Autumn Joy Sedum
1 Grass, Zebra (yellow and green)
2 Heucheras- one purple, one red or caramel
1 6pk pansies, any colors , 2 Mums, any color
1 Kale

For a smaller container, try:
– 1 kale
– 1 mum
– 2 small sedums

Remember to pull out and plant perennials in the ground if you would like to have them come back next spring. Plants are less likely to overwinter successfully in containers.